For work I need to clean up a microcassette copy the boss made with someone on the phone (which has it's own echoing artifacts, but I doubt I can do anything about that). He simply points the condenser mike at the speaker phone and then wants to be able to hear/understand the speaker on the other end. She is Chinese, which really means I need to be able to make it as clear as possible. I'm using Audacity with all manner of plug-ins (low/hi pass, EQ's (no parametric), dc offest, etc.). But as far as the phone voice...what would be the best frequencies to boost/drop to make it as clear as could be, given the questionable recording methods used? THANKS!